Technique for reducing sector sweep time for millimeter-wave devices

ABSTRACT

Certain aspects of the present disclosure provide techniques that may help reduce sector sweep time. In some cases, the techniques involve generating frames for transmission during a sector sweep procedure, each frame including one or more address fields being determined based on at least one of a transmitter address of the apparatus or a receiver address of an intended recipient of the generated frames and having fewer bits than at least one of the transmitter address or the receiver address.

CLAIM OF PRIORITY UNDER 35 U.S.C. §119

The present Application for Patent claims benefit of U.S. ProvisionalPatent Application Ser. No. 62/250,879, filed Nov. 4, 2015 and U.S.Provisional Patent Application Ser. No. 62/278,505, filed Jan. 14, 2016,each assigned to the assignee hereof and hereby expressly incorporatedby reference herein.

TECHNICAL FIELD

The invention relates generally to wireless communications systems and,more particularly, a technique for reducing sector sweep time duringbeam training in systems that utilize beamforming.

BACKGROUND

The 60 GHz band is an unlicensed band which features a large amount ofbandwidth and a large worldwide overlap. The large bandwidth means thata very high volume of information can be transmitted wirelessly. As aresult, multiple applications, each requiring transmission of largeamounts of data, can be developed to allow wireless communication aroundthe 60 GHz band. Examples for such applications include, but are notlimited to, game controllers, mobile interactive devices, wireless highdefinition TV (HDTV), wireless docking stations, wireless GigabitEthernet, and many others.

In order to facilitate such applications there is a need to developintegrated circuits (ICs) such as amplifiers, mixers, radio frequency(RF) analog circuits, and active antennas that operate in the 60 GHzfrequency range. An RF system typically comprises active and passivemodules. The active modules (e.g., a phased array antenna) requirecontrol and power signals for their operation, which are not required bypassive modules (e.g., filters). The various modules are fabricated andpackaged as radio frequency integrated circuits (RFICs) that can beassembled on a printed circuit board (PCB). The size of the RFIC packagemay range from several to a few hundred square millimeters.

In the consumer electronics market, the design of electronic devices,and thus the design of RF modules integrated therein, should meet theconstraints of minimum cost, size, power consumption, and weight. Thedesign of the RF modules should also take into consideration the currentassembled configuration of electronic devices, and particularly handhelddevices, such as laptop and tablet computers, in order to enableefficient transmission and reception of millimeter wave signals.Furthermore, the design of the RF module should account for minimalpower loss of receive and transmit RF signals and for maximum radiocoverage.

Operations in the 60 GHz band allow the use of smaller antennas ascompared to lower frequencies. However, as compared to operating inlower frequencies, radio waves around the 60 GHz band have highatmospheric attenuation and are subject to higher levels of absorptionby atmospheric gases, rain, objects, etc, resulting in higher free spaceloss. The higher free space loss can be compensated for by using manysmall antennas, for example arranged in a phased array.

Multiple antennas may be coordinated to form a coherent beam travelingin a desired direction. An electrical field may be rotated to changethis direction. The resulting transmission is polarized based on theelectrical field. A receiver may also include antennas which can adaptto match or adapt to changing transmission polarity.

SUMMARY

Certain aspects of the present disclosure provide an apparatus forwireless communications. The apparatus generally includes a processingsystem configured to generate frames for transmission during a sectorsweep procedure, each frame including one or more address fields beingdetermined based on at least one of a transmitter address of theapparatus or a receiver address of an intended recipient of thegenerated frames and having fewer bits than at least one of thetransmitter address or the receiver address, and an interface configuredto output the frames for transmission during the sector sweep procedure.

Certain aspects of the present disclosure provide an apparatus forwireless communications. The apparatus generally includes an interfaceconfigured to obtain frames during a sector sweep procedure, each frameincluding one or more address fields having fewer bits than at least oneof a transmitter address of a transmitter of the frame or a receiveraddress of an intended recipient of the frame, and a processing systemconfigured to determine at least one of the transmitter address or thereceiver address based on the one or more address fields and to processa remaining portion of the frame based on the determination.

Certain aspects of the present disclosure also provide various otherapparatus, methods, and computer readable medium for performing theoperations described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a diagram of an example wireless communicationsnetwork, in accordance with certain aspects of the present disclosure.

FIG. 2 illustrates a block diagram of an example access point and userterminals, in accordance with certain aspects of the present disclosure.

FIG. 3 illustrates a block diagram of an example wireless device, inaccordance with certain aspects of the present disclosure.

FIG. 4 illustrates an example dual polarized patch element, inaccordance with certain aspects of the present disclosure.

FIG. 5 is a diagram illustrating signal propagation in an implementationof phased-array antennas.

FIG. 5A illustrates a conventional sector sweep frame format.

FIG. 6 illustrates example operations that may be performed by anapparatus for generating frames during a sector sweep procedure, inaccordance with certain aspects of the present disclosure.

FIG. 6A illustrates components capable of performing the operationsshown in FIG. 6, in accordance with certain aspects of the presentdisclosure.

FIG. 7 illustrates example operation that may be performed by anapparatus for receiving frames during a sector sweep procedure, inaccordance with certain aspects of the present disclosure.

FIG. 7A illustrates components capable of performing the operationsshown in FIG. 7, in accordance with certain aspects of the presentdisclosure.

FIG. 8A illustrates an example of a sector sweep frame format, inaccordance with certain aspects of the present disclosure.

FIG. 8B illustrates another example sector sweep frame format, inaccordance with certain aspects of the present disclosure.

FIG. 9 illustrates examples in a tabular representation, in accordancewith certain aspects of the present disclosure, in accordance withcertain aspects of the present disclosure.

DETAILED DESCRIPTION

Aspects of the present disclosure may help reduce time during sectorsweep procedures. By reducing the length of sector sweep frames, forexample, by compressing or removing one or more fields, transmissiontime of each sector sweep frame may be reduced. As multiple sector sweepframes are typically transmitted in a sector sweep procedure, thereductions are compounded. Given that a station may perform a sectorsweep procedure with several hundred stations, reducing transmissiontime of each frame by even micro-seconds, may result in an overallreduction of several milliseconds.

Various aspects of the disclosure are described more fully hereinafterwith reference to the accompanying drawings. This disclosure may,however, be embodied in many different forms and should not be construedas limited to any specific structure or function presented throughoutthis disclosure. Rather, these aspects are provided so that thisdisclosure will be thorough and complete, and will fully convey thescope of the disclosure to those skilled in the art. Based on theteachings herein one skilled in the art should appreciate that the scopeof the disclosure is intended to cover any aspect of the disclosuredisclosed herein, whether implemented independently of or combined withany other aspect of the disclosure. For example, an apparatus may beimplemented or a method may be practiced using any number of the aspectsset forth herein. In addition, the scope of the disclosure is intendedto cover such an apparatus or method which is practiced using otherstructure, functionality, or structure and functionality in addition toor other than the various aspects of the disclosure set forth herein. Itshould be understood that any aspect of the disclosure disclosed hereinmay be embodied by one or more elements of a claim.

Although particular aspects are described herein, many variations andpermutations of these aspects fall within the scope of the disclosure.Although some benefits and advantages of the preferred aspects arementioned, the scope of the disclosure is not intended to be limited toparticular benefits, uses, or objectives. Rather, aspects of thedisclosure are intended to be broadly applicable to different wirelesstechnologies, system configurations, networks, and transmissionprotocols, some of which are illustrated by way of example in thefigures and in the following description of the preferred aspects. Thedetailed description and drawings are merely illustrative of thedisclosure rather than limiting, the scope of the disclosure beingdefined by the appended claims and equivalents thereof.

An Example Wireless Communication System

The techniques described herein may be used for various broadbandwireless communication systems, including communication systems that arebased on an orthogonal multiplexing scheme. Examples of suchcommunication systems include Spatial Division Multiple Access (SDMA),Time Division Multiple Access (TDMA), Orthogonal Frequency DivisionMultiple Access (OFDMA) systems, Single-Carrier Frequency DivisionMultiple Access (SC-FDMA) systems, and so forth. An SDMA system mayutilize sufficiently different directions to simultaneously transmitdata belonging to multiple user terminals. A TDMA system may allowmultiple user terminals to share the same frequency channel by dividingthe transmission signal into different time slots, each time slot beingassigned to different user terminal. An OFDMA system utilizes orthogonalfrequency division multiplexing (OFDM), which is a modulation techniquethat partitions the overall system bandwidth into multiple orthogonalsub-carriers. These sub-carriers may also be called tones, bins, etc.With OFDM, each sub-carrier may be independently modulated with data. AnSC-FDMA system may utilize interleaved FDMA (IFDMA) to transmit onsub-carriers that are distributed across the system bandwidth, localizedFDMA (LFDMA) to transmit on a block of adjacent sub-carriers, orenhanced FDMA (EFDMA) to transmit on multiple blocks of adjacentsub-carriers. In general, modulation symbols are sent in the frequencydomain with OFDM and in the time domain with SC-FDMA.

The teachings herein may be incorporated into (e.g., implemented withinor performed by) a variety of wired or wireless apparatuses (e.g.,nodes). In some aspects, a wireless node implemented in accordance withthe teachings herein may comprise an access point or an access terminal.

An access point (“AP”) may comprise, be implemented as, or known as aNode B, Radio Network Controller (“RNC”), evolved Node B (eNB), BaseStation Controller (“BSC”), Base Transceiver Station (“BTS”), BaseStation (“BS”), Transceiver Function (“TF”), Radio Router, RadioTransceiver, Basic Service Set (“BSS”), Extended Service Set (“ESS”),Radio Base Station (“RBS”), or some other terminology.

An access terminal (“AT”) may comprise, be implemented as, or known as asubscriber station, a subscriber unit, a mobile station (MS), a remotestation, a remote terminal, a user terminal (UT), a user agent, a userdevice, user equipment (UE), a user station, or some other terminology.In some implementations, an access terminal may comprise a cellulartelephone, a cordless telephone, a Session Initiation Protocol (“SIP”)phone, a wireless local loop (“WLL”) station, a personal digitalassistant (“PDA”), a handheld device having wireless connectioncapability, a Station (“STA”), or some other suitable processing deviceconnected to a wireless modem. Accordingly, one or more aspects taughtherein may be incorporated into a phone (e.g., a cellular phone or smartphone), a computer (e.g., a laptop), a tablet, a portable communicationdevice, a portable computing device (e.g., a personal data assistant),an entertainment device (e.g., a music or video device, or a satelliteradio), a global positioning system (GPS) device, or any other suitabledevice that is configured to communicate via a wireless or wired medium.In some aspects, the node is a wireless node. Such wireless node mayprovide, for example, connectivity for or to a network (e.g., a widearea network such as the Internet or a cellular network) via a wired orwireless communication link.

FIG. 1 illustrates a multiple-access multiple-input multiple-output(MIMO) system 100 with access points and user terminals in which aspectsof the present disclosure may be practiced.

For example, access point 110 or user terminals 120 may generate framesfor transmission during a sector sweep procedure utilizing techniquesdescribed herein. In some cases, user terminals may be game controllersor the like, and the techniques may be applied to generate frames fortransmission during a sector sweep procedure of the game controllers toa game station (acting as an access point).

For simplicity, only one access point 110 is shown in FIG. 1. An accesspoint is generally a fixed station that communicates with the userterminals and may also be referred to as a base station or some otherterminology. A user terminal may be fixed or mobile and may also bereferred to as a mobile station, a wireless device, or some otherterminology. Access point 110 may communicate with one or more userterminals 120 at any given moment on the downlink and uplink. Thedownlink (i.e., forward link) is the communication link from the accesspoint to the user terminals, and the uplink (i.e., reverse link) is thecommunication link from the user terminals to the access point. A userterminal may also communicate peer-to-peer with another user terminal. Asystem controller 130 couples to and provides coordination and controlfor the access points.

While portions of the following disclosure will describe user terminals120 capable of communicating via Spatial Division Multiple Access(SDMA), for certain aspects, the user terminals 120 may also includesome user terminals that do not support SDMA. Thus, for such aspects, anAP 110 may be configured to communicate with both SDMA and non-SDMA userterminals. This approach may conveniently allow older versions of userterminals (“legacy” stations) to remain deployed in an enterprise,extending their useful lifetime, while allowing newer SDMA userterminals to be introduced as deemed appropriate.

The system 100 employs multiple transmit and multiple receive antennasfor data transmission on the downlink and uplink. The access point 110is equipped with N_(ap) antennas and represents the multiple-input (MI)for downlink transmissions and the multiple-output (MO) for uplinktransmissions. A set of K selected user terminals 120 collectivelyrepresents the multiple-output for downlink transmissions and themultiple-input for uplink transmissions. For pure SDMA, it is desired tohave N_(ap)≧K≧1 if the data symbol streams for the K user terminals arenot multiplexed in code, frequency or time by some means. K may begreater than N_(ap) if the data symbol streams can be multiplexed usingTDMA technique, different code channels with CDMA, disjoint sets ofsubbands with OFDM, and so on. Each selected user terminal transmitsuser-specific data to and/or receives user-specific data from the accesspoint. In general, each selected user terminal may be equipped with oneor multiple antennas (i.e., N_(ut)≧1) The K selected user terminals canhave the same or different number of antennas.

The SDMA system may be a time division duplex (TDD) system or afrequency division duplex (FDD) system. For a TDD system, the downlinkand uplink share the same frequency band. For an FDD system, thedownlink and uplink use different frequency bands. MIMO system 100 mayalso utilize a single carrier or multiple carriers for transmission.Each user terminal may be equipped with a single antenna (e.g., in orderto keep costs down) or multiple antennas (e.g., where the additionalcost can be supported). The system 100 may also be a TDMA system if theuser terminals 120 share the same frequency channel by dividingtransmission/reception into different time slots, each time slot beingassigned to different user terminal 120.

FIG. 2 illustrates a block diagram of access point 110 and two userterminals 120 m and 120 x in MIMO system 100 in which aspects of thepresent disclosure may be practiced. The access point 110 is equippedwith N_(t) antennas 224 a through 224 t. User terminal 120 m is equippedwith N_(ut,m) antennas 252 ma through 252 mu, and user terminal 120 x isequipped with N_(ut,x) antennas 252 xa through 252 xu. The access point110 is a transmitting entity for the downlink and a receiving entity forthe uplink. Each user terminal 120 is a transmitting entity for theuplink and a receiving entity for the downlink. As used herein, a“transmitting entity” is an independently operated apparatus or devicecapable of transmitting data via a wireless channel, and a “receivingentity” is an independently operated apparatus or device capable ofreceiving data via a wireless channel. In the following description, thesubscript “dn” denotes the downlink, the subscript “up” denotes theuplink, Nup user terminals are selected for simultaneous transmission onthe uplink, Ndn user terminals are selected for simultaneoustransmission on the downlink, Nup may or may not be equal to Ndn, andNup and Ndn may be static values or can change for each schedulinginterval. The beam-steering or some other spatial processing techniquemay be used at the access point and user terminal.

On the uplink, at each user terminal 120 selected for uplinktransmission, a transmit (TX) data processor 288 receives traffic datafrom a data source 286 and control data from a controller 280. TX dataprocessor 288 processes (e.g., encodes, interleaves, and modulates) thetraffic data for the user terminal based on the coding and modulationschemes associated with the rate selected for the user terminal andprovides a data symbol stream. A TX spatial processor 290 performsspatial processing on the data symbol stream and provides N_(ut,m)transmit symbol streams for the N_(ut,m) antennas. Each transmitter unit(TMTR) 254 receives and processes (e.g., converts to analog, amplifies,filters, and frequency upconverts) a respective transmit symbol streamto generate an uplink signal. N_(ut,m) transmitter units 254 provideN_(ut,m) uplink signals for transmission from N_(ut,m) antennas 252 tothe access point.

Nup user terminals may be scheduled for simultaneous transmission on theuplink. Each of these user terminals performs spatial processing on itsdata symbol stream and transmits its set of transmit symbol streams onthe uplink to the access point.

At access point 110, N_(ap) antennas 224 a through 224 ap receive theuplink signals from all Nup user terminals transmitting on the uplink.Each antenna 224 provides a received signal to a respective receiverunit (RCVR) 222. Each receiver unit 222 performs processingcomplementary to that performed by transmitter unit 254 and provides areceived symbol stream. An RX spatial processor 240 performs receiverspatial processing on the N_(ap) received symbol streams from N_(ap)receiver units 222 and provides Nup recovered uplink data symbolstreams. The receiver spatial processing is performed in accordance withthe channel correlation matrix inversion (CCMI), minimum mean squareerror (MMSE), soft interference cancellation (SIC), or some othertechnique. Each recovered uplink data symbol stream is an estimate of adata symbol stream transmitted by a respective user terminal. An RX dataprocessor 242 processes (e.g., demodulates, deinterleaves, and decodes)each recovered uplink data symbol stream in accordance with the rateused for that stream to obtain decoded data. The decoded data for eachuser terminal may be provided to a data sink 244 for storage and/or acontroller 230 for further processing.

On the downlink, at access point 110, a TX data processor 210 receivestraffic data from a data source 208 for Ndn user terminals scheduled fordownlink transmission, control data from a controller 230, and possiblyother data from a scheduler 234. The various types of data may be senton different transport channels. TX data processor 210 processes (e.g.,encodes, interleaves, and modulates) the traffic data for each userterminal based on the rate selected for that user terminal. TX dataprocessor 210 provides Ndn downlink data symbol streams for the Ndn userterminals. A TX spatial processor 220 performs spatial processing (suchas a precoding or beamforming, as described in the present disclosure)on the Ndn downlink data symbol streams, and provides N_(ap) transmitsymbol streams for the N_(ap) antennas. Each transmitter unit 222receives and processes a respective transmit symbol stream to generate adownlink signal. N_(ap) transmitter units 222 providing N_(ap) downlinksignals for transmission from N_(ap) antennas 224 to the user terminals.

At each user terminal 120, N_(ut,m) antennas 252 receive the N_(ap)downlink signals from access point 110. Each receiver unit 254 processesa received signal from an associated antenna 252 and provides a receivedsymbol stream. An RX spatial processor 260 performs receiver spatialprocessing on N_(ut,m) received symbol streams from N_(ut,m) receiverunits 254 and provides a recovered downlink data symbol stream for theuser terminal. The receiver spatial processing is performed inaccordance with the CCMI, MMSE or some other technique. An RX dataprocessor 270 processes (e.g., demodulates, deinterleaves and decodes)the recovered downlink data symbol stream to obtain decoded data for theuser terminal.

At each user terminal 120, a channel estimator 278 estimates thedownlink channel response and provides downlink channel estimates, whichmay include channel gain estimates, SNR estimates, noise variance and soon. Similarly, a channel estimator 228 estimates the uplink channelresponse and provides uplink channel estimates. Controller 280 for eachuser terminal typically derives the spatial filter matrix for the userterminal based on the downlink channel response matrix Hdn,m for thatuser terminal. Controller 230 derives the spatial filter matrix for theaccess point based on the effective uplink channel response matrixHup,eff. Controller 280 for each user terminal may send feedbackinformation (e.g., the downlink and/or uplink eigenvectors, eigenvalues,SNR estimates, and so on) to the access point. Controllers 230 and 280also control the operation of various processing units at access point110 and user terminal 120, respectively.

According to certain aspects of the present disclosure, the variousprocessors shown in FIG. 2 may direct the operation at an AP 110 and/oruser terminal 120, respectively, to perform various techniques describedherein.

FIG. 3 illustrates various components that may be utilized in a wirelessdevice 302 in which aspects of the present disclosure may be practicedand that may be employed within the MIMO system 100. The wireless device302 is an example of a device that may be configured to implement thevarious methods described herein. The wireless device 302 may be anaccess point 110 or a user terminal 120.

The wireless device 302 may include a processor 304 which controlsoperation of the wireless device 302. The processor 304 may also bereferred to as a central processing unit (CPU). Memory 306, which mayinclude both read-only memory (ROM) and random access memory (RAM),provides instructions and data to the processor 304. A portion of thememory 306 may also include non-volatile random access memory (NVRAM).The processor 304 typically performs logical and arithmetic operationsbased on program instructions stored within the memory 306. Theinstructions in the memory 306 may be executable to implement themethods described herein. Processor 304 may, for example, perform ordirect operations 600 in FIG. 6 to generate frames for transmissionduring a sector sweep procedure and/or other processes for thetechniques described herein and/or may perform or direct operations 700in FIG. 7 to process such frames during a sector sweep procedure.

The wireless device 302 may also include a housing 308 that may includea transmitter 310 and a receiver 312 to allow transmission and receptionof data between the wireless device 302 and a remote location. Thetransmitter 310 and receiver 312 may be combined into a transceiver 314.A single or a plurality of transmit antennas 316 may be attached to thehousing 308 and electrically coupled to the transceiver 314. Thewireless device 302 may also include (not shown) multiple transmitters,multiple receivers, and multiple transceivers.

The wireless device 302 may also include a signal detector 318 that maybe used in an effort to detect and quantify the level of signalsreceived by the transceiver 314. The signal detector 318 may detect suchsignals as total energy, energy per subcarrier per symbol, powerspectral density and other signals. The wireless device 302 may alsoinclude a digital signal processor (DSP) 320 for use in processingsignals.

The various components of the wireless device 302 may be coupledtogether by a bus system 322, which may include a power bus, a controlsignal bus, and a status signal bus in addition to a data bus.

A beamforming process may solve one of the problems for communication atthe millimeter-wave spectrum, which is its high path loss. As such, asshown in FIG. 2, a large number of antennas are place at eachtransceiver to exploit the beamforming gain for extending communicationrange. That is, the same signal is sent from each antenna in an array,but at slightly different times.

According to an exemplary embodiment, the BF process includes a sectorlevel sweep (SLS) phase and a beam refinement stage. In the SLS phase,one of the STAs acts as an initiator by conducting an initiator sectorsweep, which is followed by a transmit sector sweep by the respondingstation (where the responding station conducts a responder sectorsweep). A sector is either a transmit antenna pattern or a receiveantenna pattern corresponding to a sector ID. As mentioned above, astation may be a transceiver that includes one or more active antennasin an antenna array (e.g., a phased antenna array).

The SLS phase typically concludes after an initiating station receivessector sweep feedback and sends a sector acknowledgement (ACK), therebyestablishing BF. Each transceiver of the initiator station and of theresponding station is configured for conducting a receiver sector sweep(RXSS) reception of sector sweep (SSW) frames via different sectors, inwhich a sweep is performed between consecutive receptions and atransmission of multiple sector sweeps (SSW) (TXSS) or directionalMulti-gigabit (DMG) beacon frames via different sectors, in which asweep is performed between consecutive transmissions.

During the beam refinement phase, each station can sweep a sequence oftransmissions, separated by a short beamforming interframe space (SBIFS)interval, in which the antenna configuration at the transmitter orreceiver can be changed between transmissions. In other words, beamrefinement is a process where a station can improve its antennaconfiguration (or antenna weight vector) both for transmission andreception. That is, each antenna includes an antenna weight vector(AWV), which further includes a vector of weights describing theexcitation (amplitude and phase) for each element of an antenna array.

FIG. 4 illustrates an example dual polarized patch element 400 which maybe employed, in accordance with certain aspects of the presentdisclosure. As shown in FIG. 4, a single element of an antenna array maycontain multiple polarized antennas. Multiple elements may be combinedtogether to form an antenna array. The polarized antennas may beradially spaced. For example, as shown in FIG. 4, two polarized antennasmay be arranged perpendicularly, corresponding to horizontally andvertically polarized antennas. Alternatively, any number of polarizedantennas may be used. Alternatively or in addition, one or both antennasof an element may also be circularly polarized.

FIG. 5 is a diagram illustrating signal propagation 500 in animplementation of phased-array antennas. Phased array antennas useidentical elements 510-1 through 510-4 (hereinafter referred toindividually as an element 510 or collectively as elements 510). Thedirection in which the signal is propagated yields approximatelyidentical gain for each element 510, while the phases of the elements510 are different. Signals received by the elements are combined into acoherent beam with the correct gain in the desired direction. Anadditional consideration of the antenna design is the expected directionof the electrical field. In case the transmitter and/or receiver arerotated with respect to each other, the electrical field is also rotatedin addition to the change in direction. This requires that a phasedarray be able to handle rotation of the electrical field by usingantennas or antenna feeds that match a certain polarity and capable ofadapting to other polarity or combined polarity in the event of polaritychanges.

Information about signal polarity can be used to determine aspects ofthe transmitter of the signals. The power of a signal may be measured bydifferent antennas that are polarized in different directions. Theantennas may be arranged such that the antennas are polarized inorthogonal directions. For example, a first antenna may be arrangedperpendicular to a second antenna where the first antenna represents ahorizontal axis and the second antenna represents a vertical axis suchthat the first antenna is horizontally polarized and the secondvertically polarized. Additional antennas may also be included, spacedat various angles in relation to each other. Once the receiverdetermines the polarity of the transmission the receiver may optimizeperformance by using the reception by matching the antenna to thereceived signal.

As noted above, a sector sweep procedure may be performed as part of anoverall beamforming (BF) training process according to, for example, theIEEE 802.11ad standard, that also involves a subsequent beamformingrefinement protocol (BRP). The BF training process is typically employedby a pair of millimeter-wave stations, e.g., a receiver and transmitter.Each pairing of the stations achieves the necessary link budget forsubsequent communication among those network devices. As such, BFtraining is a bidirectional sequence of BF training frame transmissionsthat uses sector sweep and provides the necessary signals to allow eachstation to determine appropriate antenna system settings for bothtransmission and reception. After the successful completion of BFtraining, a millimeter-wave communication link may be established withoptimal receive and/or transmit antenna settings.

Example Reduction of Sector Sweep Time

As noted above, aspects of the present disclosure may help reduce timeduring sector sweep procedures. By utilizing a compressed frame formatfor sector sweep frames (e.g., by compressing or removing one or morebits from one or more fields or removing one or more frames entirely)the transmission time of each sector sweep frame may be reduced. Thetechniques may be applied to any types of devices taking part inbeamforming training involving a sector sweep, such as game controller,mobile phones, or the like.

FIG. 5A illustrates a conventional sector sweep (SSW) frame format thatmay be used in a sector sweep procedure. As will be described in greaterdetail below with reference to FIGS. 8A and 8B, a compressed frameformat may be generated by compressing one or more of the fieldsillustrated in FIG. 5A (e.g., such that fewer bits are used to conveythe same information) or by removing one or more of the fields entirely.

According to certain aspects of the present disclosure, one or both of atransmit address (TA) and receiver address (RA) may be compressed to afewer number of bits than their combined original total. As used herein,the term address generally refers to any type of address, including whatmay be considered a conventional address (e.g., that uniquely defines adevice) or an association ID (AID) that is assigned to a station by anAP.

FIG. 6 illustrates example operations 600 that may be performed by anapparatus for generating sector sweep frames using a compressed frameformat during a sector sweep procedure, in accordance with certainaspects of the present disclosure.

The operations 600 performed by the apparatus begin at 602, bygenerating frames for transmission during a sector sweep procedure, eachframe including one or more address fields being determined based on atleast one of a transmitter address of the apparatus or a receiveraddress (combined) of an intended recipient of the generated frames andhaving fewer bits than the transmitter and the receiver addresses. Forexample, the address fields may be generated using a hash functionapplied to both the transmitter and receiver addresses (with thetransmitter and receiver addresses as input) and the resulting valueoutput may have fewer bits than the transmitter and receiver addressescombined or, in some cases, fewer bits than either the transmitteraddress or the receiver addresses. At 604, an interface outputs theframes for transmission during the sector sweep procedure.

FIG. 7 illustrates example operations 700 that may be performed by anapparatus for processing compressed sectors sweep frames during a sectorsweep procedure, in accordance with certain aspects of the presentdisclosure. In other words, operations 700 may correspond tocomplementary operations performed by a station that is participating inbeamforming training with another station generating compressed sectorsweep frames according to operations 600 described above.

The operations 700 begin, at 702, by obtaining frames during a sectorsweep procedure, each frame including one or more address fields havingfewer bits than a transmitter address of a transmitter of the frame anda receiver address (combined) of an intended recipient of the frame.

At 704, the apparatus determines at least one of the transmitter addressor the receiver address based on the address field and additionalinformation. At 706, the apparatus processes a remaining portion of theframe based on the determination.

The additional information (which may be considered “side” informationas it is not included in the frame), for example, may be one or moreactual address stored in the receiver. In such cases, the compressionapplied when generating the frame may set the value of the address fieldto select between the stored addresses. A receiving device may checkthat the receiver address indicated by the value of the address fieldmatches its own (to verify it is the intended recipient).

In some cases, the additional information may indicate a hash value usedto generate the value of the address field based on the transmitter andreceiver addresses. In this manner, the receiving device may be able todetermine what transmitter and/or receiver addresses (when the hashfunction was applied) would have resulted in the value received in theaddress field. In some cases, additional information may be provided tothe receiving device (by a transmitting device), for example, during anassociation procedure.

In some cases a compressed frame format may include an address fielddetermined based on at least one of a transmitter address of theapparatus or a receiver address of an intended recipient of thegenerated (e.g., by applying a hash function). The amount of compressionachieved in this manner may vary. For example, as shown in FIGS. 8A and8B, a transmitter address (TA) field and receiver address (RA) field, 6bytes each, may be combined to form a single field with a length of onebyte or less.

FIG. 8A illustrates an example compressed sector sweep frame format 800A(referred to herein as Option 1), in accordance with certain aspects ofthe present disclosure. This example of a compressed sector sweep frameformat may yield a reduction of 20 Bytes in frame length (andcorresponding reduction in sector sweep time). Part of the timereduction may be obtained by using a hash function. The hash function,for example, may compress a 6-byte receiver address (RA) and a 6-bytetransmission address (TA), or a total of 96-bit of addresses, to a halfbyte, or 4 bits.

The sector sweep frame format example of FIG. 8A further illustratesthat a 4-byte frame check sequence (FCS) field may be shortened to 4bits. Generally, FCS may be required for protecting data payload duringthe propagation of the payload to higher layers. However, because errorsin the sector sweep frame do not propagate to higher layers, lowerprotection can be adequately provided.

In some cases, a 3-byte sector sweep feedback may be removed in somecases because the sector sweep feedback is only needed in a respondersweep. In some cases, a sector sweep frame can include a sector sweepfield that indicates both a sector ID value and a sector sweep countdownvalue, and the sector sweep ID may equal to the sector sweep countdownnumber. In such cases, when no additional signaling for moreantennas/RXSS length/Direction is needed. As the sector sweep ID andcountdown value are typically carried in a sector sweep (SSW) field, theSSW frame length may be further reduced, for example, by compressing theSSW field from 3 bytes to 1 byte or 9 bits (e.g., by using a singlesector sweep field for both sector sweep ID and sector sweep countdown).

In some cases, a sector sweep frame may include a value indicating theaddress field is compressed. For example, a frame format type may have avalue indicating an address field has fewer bits than a transmitteraddress and a receiver address Based on a value of the frame formattype, a station may identify a compressed address field and process thecompressed address field accordingly.

In some cases, sector sweep frames may be discarded after processing(decompressing) the compressed address field. For example, a station maydiscard a frame if a receiver or transmitter address determined from anaddress field of the frame does not match any addresses of the receiveror transmitter (or if a generated FCS does not match the FCS included ina frame).

FIG. 8B illustrates another example of compressed sector sweep frameformat 800B (referred to herein as Option 2), in accordance with certainaspects of the present disclosure. The sector sweep frame format examplemay result in a 16-byte reduction in length (and corresponding reductionfrom sector sweep time).

In this example, the two 6-byte RA/TA addresses may be compressed to asingle byte (compared to the half byte shown in FIG. 8A). In thisexample, the FCS may be the same as conventional frame shown in FIG. 5A,but the sector sweep feedback can be removed and the SSW field may stillbe compressed (in other words, a sector sweep frame may lack a sectorsweep feedback field).

In another example of compressed sector sweep frame format (referred toherein as Option 3), in accordance with certain aspects of the presentdisclosure, the combined length of RA and TA may be compressed evenfurther. In this example, the RA/TA addresses may be compressed from two6-byte fields (96 bits total) to a single 2.5-byte field (20 bits). Thiscompression may be achieved, for example, using a 100 bit to 20 bit hashfunction. For associated STAs, the uncompressed RA and TA addresses willbe known, so the recipient can apply the hash function to the knownaddresses to see if the results match the value of the compressed RA/TAaddress field.

In some cases, the compressed RA and TA field may also be based on ascrambler seed or a PHY header CRC of the SSW frame. The scrambler seedmay be different per SSW procedure or per SSW frame. As such, anindication of the scrambler seed may be provided to the station. Forexample, the scrambler seed (or a hashed value generated using thescrambler seed which may also allow the station to determine thescrambler seed used) may be provided in one or more of the SSW frames(e.g., as part of the compressed address field or as a separate field).Dependency on the scrambler seed in this manner may help ensure that aSTA that incorrectly detected its own RA after uncompressing thecompressed TA/RA field will not repeat this false detection. Of course,reducing the amount of compression (e.g., using more bits for the outputof the hash function) may further reduce the chances for a false RAmatch.

As illustrated in FIG. 8A, the FCS field may also be compressed, forexample, from 4 bytes to half a byte (4 bits), which may have arelatively low impact on false positives. The duration field and sectorsweep feedback field may also be removed (so the SSW frame lacks thesefields). In some cases, the duration field may be compressed by eitherquantization to lower resolution (e.g., greater than 1 us so fewer bitsare needed to indicate a given duration) or use a same resolution with ashorter length (meaning a shorter maximum duration can be indicated),for example, taking the countdown ID into consideration.

As illustrated, the SSW field may also be compressed (e.g., from 3 bytesto 1.5 bytes). This SSW compression may be achieved, for example, byusing a 12 bit countdown field, with 10 bits for sectors and 2 bits forantennas (or some other similar type bit allocation).

FIG. 9 illustrates a table 900 listing example reductions of sectorsweep time that may be accomplished using the frame formats shown inFIGS. 8A and 8B, relative to the conventional frame format shown in FIG.5A.

As illustrated, by utilizing Option 1 illustrated in FIG. 8A, reductionsof up to 37% may be achieved, while utilizing Option 2 illustrated inFIG. 8B, may yield reductions of up to 15%. The exact yield achieved mayrepresent a tradeoff between reductions in transmission time and anincrease probability of undetected errors. Further, the reduction insector sweep time may be orthogonal (e.g., independent of) to othermethods that reduce the sector sweep time.

Because there can be hundreds of sectors that need to be sweep during asector sweep procedure, the accumulative time reduction in sector sweeptime using the compressed frame formats described herein during a sectorsweep procedure can be significant. For example, a device with arelatively large antenna array may need additional sectors to be usedfor training, and an access point (AP) with 256 antennas that use 256sectors may spend 4 ms for sector sweep. Thus, the aggregate sectorsweep time for training of 10 STAs can be greater than 40 ms. Therefore,utilizing the compressed frame formats described herein to reducetransmission time of each frame may result in significant performanceimprovements.

The various operations of methods described above may be performed byany suitable means capable of performing the corresponding functions.The means may include various hardware and/or software component(s)and/or module(s), including, but not limited to a circuit, anapplication specific integrated circuit (ASIC), or processor. Generally,where there are operations illustrated in figures, those operations mayhave corresponding counterpart means-plus-function components withsimilar numbering. For example, operations 600 and 700 illustrated inFIGS. 6 and 7 correspond to means 600A and 700A illustrated in FIGS. 6Aand 7A.

For example, means for transmitting (or means for outputting fortransmission) may comprise a transmitter (e.g., the transmitter unit222) and/or an antenna(s) 224 of the access point 110 or the transmitterunit 254 and/or antenna(s) 252 of the user terminal 120 illustrated inFIG. 2. Means for receiving (or means for obtaining) may comprise areceiver (e.g., the receiver unit 222) and/or an antenna(s) 224 of theaccess point 110 or the receiver unit 254 and/or antenna(s) 254 of theuser terminal 120 illustrated in FIG. 2. Means for processing, means forobtaining, means for generating, means for selecting, means fordecoding, means for causing, means for servicing, means for assigning,means for re-assigning, or means for determining, may comprise aprocessing system, which may include one or more processors, such as theRX data processor 242, the TX data processor 210, the TX spatialprocessor 220, and/or the controller 230 of the access point 110 or theRX data processor 270, the TX data processor 288, the TX spatialprocessor 290, and/or the controller 280 of the user terminal 120illustrated in FIG. 2.

In some cases, rather than actually transmitting a frame a device mayhave an interface to output a frame for transmission (a means foroutputting). For example, a processor may output a frame, via a businterface, to a radio frequency (RF) front end for transmission.Similarly, rather than actually receiving a frame, a device may have aninterface to obtain a frame received from another device (a means forobtaining). For example, a processor may obtain (or receive) a frame,via a bus interface, from an RF front end for reception.

According to certain aspects, such means may be implemented byprocessing systems configured to perform the corresponding functions byimplementing various algorithms (e.g., in hardware or by executingsoftware instructions) described above for generating frames fortransmission during a sector sweep procedure.

As used herein, the term “generating” encompasses a wide variety ofactions. For example, “generating” may include calculating, causing,computing, creating, determining, processing, deriving, investigating,making, producing, providing, giving rise to, leading to, resulting in,looking up (e.g., looking up in a table, a database or another datastructure), ascertaining and the like. Also, “generating” may includereceiving (e.g., receiving information), accessing (e.g., accessing datain a memory) and the like. Also, “generating” may include resolving,selecting, choosing, establishing and the like.

As used herein, the term “determining” encompasses a wide variety ofactions. For example, “determining” may include calculating, computing,processing, deriving, investigating, looking up (e.g., looking up in atable, a database or another data structure), ascertaining and the like.Also, “determining” may include receiving (e.g., receiving information),accessing (e.g., accessing data in a memory) and the like. Also,“determining” may include resolving, selecting, choosing, establishingand the like. Also, “determining” may include measuring, estimating andthe like.

As used herein, a phrase referring to “at least one of” a list of itemsrefers to any combination of those items, including single members. Asan example, “at least one of: a, b, or c” is intended to cover a, b, c,a-b, a-c, b-c, and a-b-c, as well as any such list including multiplesof the same members (e.g., any lists that include aa, bb, or cc).

The various illustrative logical blocks, modules and circuits describedin connection with the present disclosure may be implemented orperformed with a general purpose processor, a digital signal processor(DSP), an application specific integrated circuit (ASIC), a fieldprogrammable gate array (FPGA) or other programmable logic device (PLD),discrete gate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.A general-purpose processor may be a microprocessor, but in thealternative, the processor may be any commercially available processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

The steps of a method or algorithm described in connection with thepresent disclosure may be embodied directly in hardware, in a softwaremodule executed by a processor, or in a combination of the two. Asoftware module may reside in any form of storage medium that is knownin the art. Some examples of storage media that may be used includerandom access memory (RAM), read only memory (ROM), flash memory, EPROMmemory, EEPROM memory, registers, a hard disk, a removable disk, aCD-ROM and so forth. A software module may comprise a singleinstruction, or many instructions, and may be distributed over severaldifferent code segments, among different programs, and across multiplestorage media. A storage medium may be coupled to a processor such thatthe processor can read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor.

The methods disclosed herein comprise one or more steps or actions forachieving the described method. The method steps and/or actions may beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isspecified, the order and/or use of specific steps and/or actions may bemodified without departing from the scope of the claims.

The functions described may be implemented in hardware, software,firmware, or any combination thereof. If implemented in hardware, anexample hardware configuration may comprise a processing system in awireless node. The processing system may be implemented with a busarchitecture. The bus may include any number of interconnecting busesand bridges depending on the specific application of the processingsystem and the overall design constraints. The bus may link togethervarious circuits including a processor, machine-readable media, and abus interface. The bus interface may be used to connect a networkadapter, among other things, to the processing system via the bus. Thenetwork adapter may be used to implement the signal processing functionsof the PHY layer. In the case of a user terminal 120 (see FIG. 1), auser interface (e.g., keypad, display, mouse, joystick, etc.) may alsobe connected to the bus. The bus may also link various other circuitssuch as timing sources, peripherals, voltage regulators, powermanagement circuits, and the like, which are well known in the art, andtherefore, will not be described any further.

The processor may be responsible for managing the bus and generalprocessing, including the execution of software stored on themachine-readable media. The processor may be implemented with one ormore general-purpose and/or special-purpose processors. Examples includemicroprocessors, microcontrollers, DSP processors, and other circuitrythat can execute software. Software shall be construed broadly to meaninstructions, data, or any combination thereof, whether referred to assoftware, firmware, middleware, microcode, hardware descriptionlanguage, or otherwise. Machine-readable media may include, by way ofexample, RAM (Random Access Memory), flash memory, ROM (Read OnlyMemory), PROM (Programmable Read-Only Memory), EPROM (ErasableProgrammable Read-Only Memory), EEPROM (Electrically ErasableProgrammable Read-Only Memory), registers, magnetic disks, opticaldisks, hard drives, or any other suitable storage medium, or anycombination thereof. The machine-readable media may be embodied in acomputer-program product. The computer-program product may comprisepackaging materials.

In a hardware implementation, the machine-readable media may be part ofthe processing system separate from the processor. However, as thoseskilled in the art will readily appreciate, the machine-readable media,or any portion thereof, may be external to the processing system. By wayof example, the machine-readable media may include a transmission line,a carrier wave modulated by data, and/or a computer product separatefrom the wireless node, all which may be accessed by the processorthrough the bus interface. Alternatively, or in addition, themachine-readable media, or any portion thereof, may be integrated intothe processor, such as the case may be with cache and/or generalregister files.

The processing system may be configured as a general-purpose processingsystem with one or more microprocessors providing the processorfunctionality and external memory providing at least a portion of themachine-readable media, all linked together with other supportingcircuitry through an external bus architecture. Alternatively, theprocessing system may be implemented with an ASIC (Application SpecificIntegrated Circuit) with the processor, the bus interface, the userinterface in the case of an access terminal), supporting circuitry, andat least a portion of the machine-readable media integrated into asingle chip, or with one or more FPGAs (Field Programmable Gate Arrays),PLDs (Programmable Logic Devices), controllers, state machines, gatedlogic, discrete hardware components, or any other suitable circuitry, orany combination of circuits that can perform the various functionalitydescribed throughout this disclosure. Those skilled in the art willrecognize how best to implement the described functionality for theprocessing system depending on the particular application and theoverall design constraints imposed on the overall system.

The machine-readable media may comprise a number of software modules.The software modules include instructions that, when executed by theprocessor, cause the processing system to perform various functions. Thesoftware modules may include a transmission module and a receivingmodule. Each software module may reside in a single storage device or bedistributed across multiple storage devices. By way of example, asoftware module may be loaded into RAM from a hard drive when atriggering event occurs. During execution of the software module, theprocessor may load some of the instructions into cache to increaseaccess speed. One or more cache lines may then be loaded into a generalregister file for execution by the processor. When referring to thefunctionality of a software module below, it will be understood thatsuch functionality is implemented by the processor when executinginstructions from that software module.

If implemented in software, the functions may be stored or transmittedover as one or more instructions or code on a computer-readable medium.Computer-readable media include both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. A storage medium may be anyavailable medium that can be accessed by a computer. By way of example,and not limitation, such computer-readable media can comprise RAM, ROM,EEPROM, CD-ROM or other optical disk storage, magnetic disk storage orother magnetic storage devices, or any other medium that can be used tocarry or store desired program code in the form of instructions or datastructures and that can be accessed by a computer. Also, any connectionis properly termed a computer-readable medium. For example, if thesoftware is transmitted from a website, server, or other remote sourceusing a coaxial cable, fiber optic cable, twisted pair, digitalsubscriber line (DSL), or wireless technologies such as infrared (IR),radio, and microwave, then the coaxial cable, fiber optic cable, twistedpair, DSL, or wireless technologies such as infrared, radio, andmicrowave are included in the definition of medium. Disk and disc, asused herein, include compact disc (CD), laser disc, optical disc,digital versatile disc (DVD), floppy disk, and Blu-ray® disc where disksusually reproduce data magnetically, while discs reproduce dataoptically with lasers. Thus, in some aspects computer-readable media maycomprise non-transitory computer-readable media (e.g., tangible media).In addition, for other aspects computer-readable media may comprisetransitory computer-readable media (e.g., a signal). Combinations of theabove should also be included within the scope of computer-readablemedia.

Thus, certain aspects may comprise a computer program product forperforming the operations presented herein. For example, such a computerprogram product may comprise a computer-readable medium havinginstructions stored (and/or encoded) thereon, the instructions beingexecutable by one or more processors to perform the operations describedherein. For certain aspects, the computer program product may includepackaging material.

Further, it should be appreciated that modules and/or other appropriatemeans for performing the methods and techniques described herein can bedownloaded and/or otherwise obtained by a user terminal and/or basestation as applicable. For example, such a device can be coupled to aserver to facilitate the transfer of means for performing the methodsdescribed herein. Alternatively, various methods described herein can beprovided via storage means (e.g., RAM, ROM, a physical storage mediumsuch as a compact disc (CD) or floppy disk, etc.), such that a userterminal and/or base station can obtain the various methods uponcoupling or providing the storage means to the device. Moreover, anyother suitable technique for providing the methods and techniquesdescribed herein to a device can be utilized.

It is to be understood that the claims are not limited to the preciseconfiguration and components illustrated above. Various modifications,changes and variations may be made in the arrangement, operation anddetails of the methods and apparatus described above without departingfrom the scope of the claims.

What is claimed is:
 1. An apparatus for wireless communications,comprising: a processing system configured to generate frames fortransmission during a sector sweep procedure, each frame including oneor more address fields being determined based on at least one of atransmitter address of the apparatus or a receiver address of anintended recipient of the generated frames and having fewer bits thanthe transmitter address and the receiver address combined; and aninterface configured to output the frames for transmission during thesector sweep procedure.
 2. The apparatus of claim 1, wherein each framealso includes a sector sweep field that indicates both a sector ID valueand a sector sweep countdown value.
 3. The apparatus of claim 2, whereinthe sector ID value and sector sweep countdown value are the same. 4.The apparatus of claim 1, wherein each frame also includes a sectorsweep field that has a first number of one or more bits to indicate acountdown value for a sector ID and a second number of one or more bitsto indicate a countdown for an antenna configuration.
 5. The apparatusof claim 1, wherein each frame also includes a frame check sequence(FCS) comprising a length of less than 4 bytes.
 6. The apparatus ofclaim 1, wherein each frame lacks a sector sweep feedback field.
 7. Theapparatus of claim 1, wherein the processing system is configured todetermine the one or more address fields based on a hash functionapplied to at least one of the transmitter address or the receiveraddress.
 8. The apparatus of claim 1, wherein the processing system isconfigured to generate the one or more address fields based, at least inpart, on one or more scrambler seeds to be used to scramble the framesprior to transmission.
 9. The apparatus of claim 8, wherein the one ormore address fields, in at least one of the frames, comprise: a firstaddress value that is independent of a scrambler seed; and a secondaddress value generated based on the first address value and a scramblerseed.
 10. The apparatus of claim 1, wherein the processing system isconfigured to generate the one or more address fields based, at least inpart, on check values generated for a header portion of the frames. 11.The apparatus of claim 1, wherein each of the frames comprises a fieldhaving a frame format type with a value indicating the one or moreaddress fields have fewer bits than the transmitter address and thereceiver address combined.
 12. An apparatus for wireless communications,comprising: an interface configured to obtain frames during a sectorsweep procedure, each frame including one or more address fields havingfewer bits than a transmitter address of a transmitter of the frame anda receiver address of an intended recipient of the frame; and aprocessing system configured to determine at least one of thetransmitter address or the receiver address, based on the one or moreaddress fields and additional information, and to process a remainingportion of the frame based on the determination.
 13. The apparatus ofclaim 12, wherein: the additional information comprises one or moreaddresses stored at the apparatus; and a value of the one or moreaddress fields indicates one of the stored addresses.
 14. The apparatusof claim 12, wherein the processing system is configured to discard oneof the frames if at least one of: a receiver address determined based onthe one or more address fields of that frame does not match an addressof the apparatus; or a transmitter address determined based on the oneor more address fields of that frame does not match the address of adesired transmitter.
 15. The apparatus of claim 12, wherein: each framealso includes a sector sweep field; and the processing system isconfigured to determine both a sector ID value and a sector sweepcountdown value based on the sector sweep field and update a status ofthe sector sweep procedure based on the sector ID value and the sectorsweep countdown value.
 16. The apparatus of claim 15, wherein the sectorID value and sector sweep countdown value are the same.
 17. Theapparatus of claim 12, wherein: each frame also includes a frame checksequence (FCS) comprising a length of less than 4 bytes; and theprocessing system is configured to generate, for each frame, an FCSbased on the frame and to discard the frame if the generated FCS doesnot match the FCS included in the frame.
 18. The apparatus of claim 12,wherein: the processing system is configured to apply a hash function toat least one of the transmitter address or the receiver address and tocompare results obtained from the application to the one or moreaddresses; and the determination is based on the comparison.
 19. Theapparatus of claim 12, wherein: each of the frames comprises a fieldhaving a frame format type; and the processing system is configured toidentify, based on a value of the frame format type, that the one ormore address fields has fewer bits than at least one of the transmitteraddress or the receiver address and to process the one or more addressfields based on the identification.
 20. The apparatus of claim 19,wherein the processing system is further configured to process at leastone of a sector sweep field of the obtained frame or frame checksequence (FCS) field of the obtained frame based on the identification.21. The apparatus of claim 12, wherein the determination is furtherbased on one or more scrambler seeds.
 22. The apparatus of claim 21,wherein: the one or more address fields, in at least one of the frames,comprise a first address value that is independent of a scrambler seedand a second address value generated based on the first address valueand a scrambler seed; and the processing system is configured todetermine the scrambler seed based on the second value, wherein the oneor more scrambler seeds comprise the determined scrambler seed. 23-70.(canceled)
 71. A wireless node, comprising: a processing systemconfigured to generate frames for transmission during a sector sweepprocedure, each frame including one or more address fields beingdetermined based on at least one of a transmitter address of thewireless node or a receiver address of an intended recipient of thegenerated frames and having fewer bits than the transmitter address andthe receiver address; and a transmitter configured to transmit theframes for transmission during the sector sweep procedure.